Reticle piece having level indicating device

Abstract

An improved reticle piece for use in an optical sight, placed at either the first or second focal plane, and an associated method of manufacturing. The reticle piece includes a first portion having a front face, a second portion having a back face disposed opposite the front face, a housing, a reticle pattern on the second portion, and a moveable leveling indicator. The housing includes a spacing element that forms a cavity extending between the first and second portions, the cavity having a perimeter that defines a viewable area of the reticle piece. The moveable leveling indicator is within the cavity and capable of moving along at least a portion of the perimeter of the cavity, possibly moving along the entire perimeter of the cavity.

What is claimed is: 
     
       1. A reticle piece for use in an optical sight, comprising:
 a first portion having a front face; 
 a second portion having a back face disposed opposite the front face; 
 a housing including a spacing element that forms a cavity extending between the first and second portions, the cavity having a perimeter that defines a viewable area of the reticle piece; 
 a reticle pattern on the second portion; and 
 a moveable leveling indicator within the cavity and capable of moving along at least a portion of the perimeter of the cavity. 
 
     
     
       2. The reticle piece of  claim 1 , further comprising a third portion disposed between the first and second portions, such that the cavity is formed between the first and third portions and the reticle pattern is on one of the second or third portions. 
     
     
       3. The reticle piece of  claim 1 , wherein the spacing element includes front and back sealing elements and a projection therebetween. 
     
     
       4. The reticle piece of  claim 1 , further comprising front and back locking elements, wherein the front locking element couples the first portion to the housing and the back locking element couples the second portion to the housing. 
     
     
       5. The reticle piece of  claim 1 , wherein the second portion further comprises a second inner face disposed opposite the back face, such that the reticle pattern is on the second inner face. 
     
     
       6. The reticle piece of  claim 1 , wherein the moveable leveling indicator is capable of moving along the entire perimeter of the cavity. 
     
     
       7. The reticle piece of  claim 1 , wherein the moveable leveling indicator further comprises a bubble trapped in a fluid. 
     
     
       8. The reticle piece of  claim 1 , wherein the moveable leveling indicator further comprises a microsphere trapped in a fluid. 
     
     
       9. The reticle piece of  claim 8 , wherein the densities of the microsphere and the fluid are within 10% of each other, either causing the microsphere to float or sink in the fluid. 
     
     
       10. The reticle piece of  claim 8 , wherein the fluid comprises about 70-90% of Ethyl Alcohol, about 0-10% of a solute of a surfactant, and about 9-29% of Propylene Carbonate. 
     
     
       11. The reticle piece of  claim 8 , wherein the fluid comprises about 80% of Ethyl Alcohol, about 1% of a solute of a surfactant, and about 19% of Propylene Carbonate. 
     
     
       12. The reticle piece of  claim 8 , wherein the fluid comprises more than 90% of Ethyl Acetate and less than 10% of a solute of a surfactant, and preferably about 99% of Ethyl Acetate and about 1% of a solute of a surfactant. 
     
     
       13. The reticle piece of  claim 8 , wherein the fluid consists of 100% Ethyl Acetate. 
     
     
       14. The reticle piece of  claim 8 , wherein the fluid consists of 100% Propylene Carbonate. 
     
     
       15. The reticle piece of  claim 1 , wherein the reticle piece further includes indicia marking a position of the moveable leveling indicator when the reticle piece is level. 
     
     
       16. The reticle piece of  claim 15 , wherein the indicia is formed on the reticle piece and further includes gradation units of tilt. 
     
     
       17. The reticle piece of  claim 1 , wherein the housing further comprises an illumination port configured to receive light from a light source allowing for the reticle pattern to be illuminated. 
     
     
       18. A method of manufacturing a reticle piece for use in an optical sight, the reticle piece including first, second and third portions, a moveable leveling indicator, front and back locking elements, and a housing including a projection having first and second sides, the method comprising:
 inserting the third portion into the housing adjacent the rear side of the projection; 
 inserting the second portion into the housing adjacent the third portion; 
 coupling the back locking element to the housing to secure the second and third portions; 
 inserting a moveable leveling indicator into a cavity formed by the third portion and a spacing element; 
 filling the cavity with a fluid; 
 inserting the second portion adjacent the front side of the projection to enclose the cavity; and 
 coupling the front locking element to the housing to secure the first portion. 
 
     
     
       19. The method of  claim 18 , wherein filling the cavity further comprises overflowing the cavity with the fluid to form a meniscus that prevents air from being introduced into the cavity when the second portion is subsequently inserted. 
     
     
       20. The method of  claim 18 , wherein the spacing element includes front and back sealing elements with the projection therebetween, the method further comprising:
 inserting the back sealing element adjacent a back face of the projection prior to inserting the third portion into the housing; and 
 inserting the front sealing element adjacent a front face of the projection prior to inserting the moveable leveling indicator.